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VB.NET SafeFileHandle构造函数代码示例

本文整理汇总了VB.NET中Microsoft.Win32.SafeHandles.SafeFileHandle.SafeFileHandle构造函数的典型用法代码示例。如果您正苦于以下问题:VB.NET SafeFileHandle构造函数的具体用法?VB.NET SafeFileHandle怎么用?VB.NET SafeFileHandle使用的例子?那么恭喜您, 这里精选的构造函数代码示例或许可以为您提供帮助。您也可以进一步了解该构造函数所在Microsoft.Win32.SafeHandles.SafeFileHandle的用法示例。


在下文中一共展示了SafeFileHandle构造函数的1个代码示例,这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞,您的评价将有助于系统推荐出更棒的VB.NET代码示例。

示例1: SafeHandlesExample

' 导入命名空间
Imports Microsoft.Win32.SafeHandles
Imports System.Runtime.InteropServices
Imports System.ComponentModel



Class SafeHandlesExample


    Shared Sub Main()
        Try

            Dim loader As New UnmanagedFileLoader("example.xml")


        Catch e As Exception
            Console.WriteLine(e)
        End Try
        Console.ReadLine()

    End Sub
End Class


Class UnmanagedFileLoader

    Public Const FILE_ATTRIBUTE_NORMAL As Short = &H80
    Public Const INVALID_HANDLE_VALUE As Short = -1
    Public Const GENERIC_READ As Long = &H80000000
    Public Const GENERIC_WRITE As UInteger = &H40000000
    Public Const CREATE_NEW As UInteger = 1
    Public Const CREATE_ALWAYS As UInteger = 2
    Public Const OPEN_EXISTING As UInteger = 3


    ' Use interop to call the CreateFile function.
    ' For more information about CreateFile,
    ' see the unmanaged MSDN reference library.
    <DllImport("kernel32.dll", SetLastError:=True, CharSet:=CharSet.Unicode)> _
    Private Shared Function CreateFile(ByVal lpFileName As String, ByVal dwDesiredAccess As System.UInt32, ByVal dwShareMode As System.UInt32, ByVal lpSecurityAttributes As IntPtr, ByVal dwCreationDisposition As System.UInt32, ByVal dwFlagsAndAttributes As System.UInt32, ByVal hTemplateFile As IntPtr) As IntPtr

    End Function

    Private handleValue As SafeFileHandle = Nothing



    Public Sub New(ByVal Path As String)
        Load(Path)

    End Sub


    Public Sub Load(ByVal Path As String)
        If Path Is Nothing AndAlso Path.Length = 0 Then
            Throw New ArgumentNullException("Path")
        End If

        ' Try to open the file.

        Dim ptr As IntPtr = CreateFile(Path, GENERIC_WRITE, 0, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero)

        handleValue = New SafeFileHandle(ptr, True)
        ' If the handle is invalid,
        ' get the last Win32 error 
        ' and throw a Win32Exception.
        If handleValue.IsInvalid Then
            Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error())
        End If

    End Sub


    Public ReadOnly Property Handle() As SafeFileHandle
        Get
            ' If the handle is valid,
            ' return it.
            If Not handleValue.IsInvalid Then
                Return handleValue
            Else
                Return Nothing
            End If
        End Get
    End Property
End Class
开发者ID:VB.NET开发者,项目名称:Microsoft.Win32.SafeHandles,代码行数:86,代码来源:SafeFileHandle


注:本文中的Microsoft.Win32.SafeHandles.SafeFileHandle.SafeFileHandle构造函数示例由纯净天空整理自Github/MSDocs等开源代码及文档管理平台,相关代码片段筛选自各路编程大神贡献的开源项目,源码版权归原作者所有,传播和使用请参考对应项目的License;未经允许,请勿转载。